The short answer is massively better performance for some workloads. Database reports than took hours on x86 systems, and run in minutes on optimized SPARC-based systems, for example.
General-purpose hardware is fine for general-purpose problems, but at a certain point, for certain workloads, it runs out of steam. Not that the x86/Linux folks who've never used really big systems want to believe that, of course.
Biting the hand that feeds IT
